I've downloaded the package and run it, with the result being a folder in the Applications folder with various commands in it. When I double-click 'get_iplayer.command' a Terminal window opens and I get the following error:

As you're told in the install docs, only macOS system Perl is supported. If you use an unsupported Perl installation, it is your responsibility to configure it properly. The modules you need are listed in the documentation.

I wasn't aware that I had non-standard Perl installation. Presumably it's a side-effect of something else I've installed at some stage. So now I'll try to work out how to put it back to how it should be...